Slide 2 Lake Nipissing: Ecology & Fisheries Richard Rowe,
Senior Biologist Slide 3 Lake Nipissing: The Last 100 Years
Pre-World War I: Blue phase, shadflies & sturgeon decline World
War I: The Beef & Bacon Initiative 1940s & 1950s Tourism,
Yellow seeding, 1 st Blue-Green report 1960s & 1970s Tourism
explosion, Fisheries assessment, ice fishing, blue phased out Slide
4 Lake Nipissing: The Last 100 Years 1980s to mid 1990s
Recreational fishing concern, NFN commercial fishery emerging Mid
1990s to early 2000s NFN commercial fishery concern, loss of
fisheries assessment Mid 2000s to 2010 Significant Management
Efforts, Walleye fishery slowly improving? 2010-present Walleye
fishery decline, ecosystem shifts Slide 5 Habitat Changes The
creeping crisis Loss of diversity; loss of insurance Slide 6
Species Introductions & Re-colonization Always a risk of
upsetting the ecosystem balance Slide 7 Most Recent Changes in
Ecosystem Arguably the biggest changes: Other Notable Changes:
Energy Flow changes in food web from zooplankton to walleye Herring
Smelt Walleye observed feeding on smelt; growth changes, movements?
Slide 8 Present Day Lake Nipissing Ecosystem: The Walleye
Lake-wide, the top predator and greatest top-down influence on
ecosystem (this could be changing) The most significant population
stress on Lake Nipissing walleye continues to be human exploitation
Slide 9 Monitoring the Walleye & the Impacts We Have On It Fall
Walleye Index Netting (FWIN) Daily Commercial Harvest Reporting
Angler Creel Surveys (Other data sets, other species) Slide 10 Q:
How do you manage walleye? A: You Dont Fish manage themselves we
try to manage our impacts when needed. Best way to manage impacts
on walleye: Protect spawning population = protect the future
Walleye Management - Considerations Slide 11 The Reasons are in the
biology: A 4-lb female lays 100,000 eggs So? If there are enough
adult walleye left and they spawn, they can increase the population
quickly (IF conditions are right and IF there are enough) Lake
Nipissing is ideal habitat for walleye So? If weather conditions
are suitable and there is a enough spawning fish, Lake Nipissing
walleye will produce strong year classes The Key to Management Keep
Enough Spawning Fish in the Lake Slide 12 Approach: Adaptive
Management A combination of science and trial and error The
Science: Maximum Sustainable Yield The Trial/Error: Maintain a
harvest significantly lower than this, protect spawning fish and
see what happens Harvest Level Stock Status CriticalCautiousHealthy
Total Harvest Level Maximum Harvest Level Limit Reference Point
Upper Stock Reference Point Slide 13 Angler Harvest Control
directed at Spawning Fish Recreational angling fishery protected
slot size Angling season opens after spawn Slide 14 NFN Management
efforts to protect spawning walleye Mesh size (minimizes kill of
larger spawners) Moratorium (guarantee fish left to spawn) Quota
(guarantee fish left to spawn) Reporting harvest (keeping track)
Slide 15 Signs of Modern Management Working? Since 2004 (when slot
started/NFN started): Spawning stock every year for 5 years in a
row (numbers and biomass) Slide 16 Signs of Management Working?
Despite all other stresses on ecosystem to this point, management
efforts seemed to be working Index Nets wt. walleye > 40 cm NFN
formal mgmt Slot Size Slide 17 Harvest seems to be at level that
allows slow increase of spawning stock Harvest (kg) Estimated Safe
Harvest Level (Maximum sustainable) Total of all walleye harvested
(sport + commercial) NFN formal mgmt Slot Size Slide 18 Something
happened in 2009 Number of spawning walleye in index netting
Management stayed the same reported harvest at desired level
Suspicion that ecosystem was changingagain One bad year of data or
was this a real change? Slide 19 THE Alarming Trend: Spawning Stock
Slide 20 Slide 21 What Happened? Many contributing factors likely
played a role: harvest, ecosystem, nature cycles No one specific
cause for the latest decline Slide 22 Harvest STILL Drives the
Fishery? Slide 23 Slide 24 Slide 25 Slide 26 Slide 27 Slide 28
Slide 29 IF Harvest Still Drives Fishery: Extra harvest had to
occur in 2009 and 2010 X X Slide 30 Can we find extra or unexpected
harvest in 2009, 2010 to make sense of existing data? Confirmed
Sources: Non-compliance NFN moratorium (ballpark #s based on
occurrences) Commercial spearing possibilities (ballpark numbers
based on weather) Undetected angler non-compliance with slot size
(ballpark numbers based on Alberta model) Dokis FN
commercialization (ballpark #s based on confirmed reports) Slide 31
Extra Harvest Factor: Slide 32 Slide 33 What Happened - Final
Thoughts Should we have done more in 1998; 2004? Did we let our
collective guard down for compliance during a time when it was
needed most? Did we live off the principle of the fishery during
times of record low interest? Did we get unlucky from a weather and
cyclical perspective? Varying degrees of Yes to all of these Slide
34 Where Does This Leave Us Moving Forward? The Ecosystem In a
state of flux SWF abundant, Yellow perch dominant, Walleyes place
uncertain Slide 35 Where Does This Leave Us Moving Forward? The
Walleye Fishery Seem to be skinnier; maturing a bit later This +
the double gauntlet is leading to or has led to a serious situation
called recruitment overfishing Slide 36 Age 0-1Age 2-3Age 3-4Age
5-7Age 8+ Slide 37 Age 0-1Age 2-3Age 3-4Age 5-7Age 8+ Slide 38 Age
0-1Age 2-3Age 3-4Age 5-7Age 8+ ? Recruitment Overfishing Slide 39
Where Does This Leave Us Moving Forward? The Challenge for the
Future Record numbers of young captured in FWIN 2 yrs in a row Can
we get them through to become prime spawning stock? Slide 40 Where
Does This Leave Us Moving Forward? The Challenge for the Future
Record numbers of young captured in FWIN 2 yrs in a row Can we get
them through to become prime spawning stock? Slide 41 Where Does
This Leave Us Moving Forward? The Challenge for the Future How do
we assure that enough of these young make it through? Chances for
success depends on both major fisheries IF we make it through how
do we get better compliance during those lean years? Slide 42 The
Next 5 Years: Our Biggest Crisis or Our Greatest Opportunity?
